This invention relates to an x-ray tube target assembly, and more particularly to a rotary metal-graphite composite target having integrally attached heat shields.
Rotary metal-graphite composite target assemblies for x-ray tubes have been known in prior art. For example, the U.S. Pat. No. 4,901,338, discloses this type of assembly, that comprises an annular graphite substrate which is secured to the back surface of a disk-shaped target made, for example, of a metal material such as tungsten, molybdenum or related alloys, such as TZM. A rotary shaft supported by bearings is secured to the disk-shaped target and passes through the central opening of the annular graphite substrate. Since the heat from the target can adversely affect the lifetime of the bearings and as a result the x-ray tube as a whole, the portion of outer surface of the shaft inside the annular graphite substrate is covered with a heat-insulating material. This protection is not sufficient to adequately shield the shaft and the bearings from the heat generated by the graphite substrate.